Jet dyeing machines, as representatively described in U.S. Pat. No. 3,780,544, are widely used throughout textile producing areas of the world. Although there have been advances in this art area since the early 1970's when these machines first became popular, many of the pre-1980 jet dyeing machines are still in extensive use. A representative dyeing machine of the prior art is shown in FIGS. 5 and 5A.
A jet dyeing machine made prior to 1978 typically has a pressure vessel 1 which is about seven feet in diameter. Within the pressure vessel 1 is one or more prior art inner chambers 22, each containing an endless rope of fabric 5 which is dyed as it circulates through the jet dyeing machine. The endless rope of fabric 5 is plaited or folded in the prior art inner chamber 22 and floats in a bath of dye liquid. By floating the endless rope of fabric 5 in a bath, the strain on the fabric is reduced.
The endless rope of fabric 5 is lifted from the floating plug by a lifter reel 23 contained within a lifter reel housing 6. The lifter reel 23 frequently consists of a series of spokes which catch and move the fabric as they rotate. The endless rope of fabric 5 then goes to a jet dyeing chamber 7 where a jet venturi (not shown) introduces dye liquid to the fabric. The endless rope of fabric 5 then moves to the cloth discharge tube 20 where the dye liquid and the fabric return to the prior art inner chamber 22. As shown in FIG. 5A, prior art cloth discharge tubes 20 normally require the endless rope of fabric 5 to make a sharp turn which can impede the fabric's progress as it re-enters the prior art inner chamber 22.
Dye is recirculated from an end wall pump header or opening 12 which leads to the pump and pump housing 14. The pump lifts dye liquor through the heat exchanger 15 and sends it through the manifold 16 which distributes the dye to the jet dyeing chambers 7. Each pressure vessel 1 on a prior art jet dyeing machine typically has more than one prior art inner chamber 22. For each prior art inner chamber 22 there is an associated lifter reel 23 and jet dyeing chamber 7. The prior art jet dyeing machine typically has a relatively small existing drain pipe 18 located beneath the pressure vessel 1.
These prior art jet dyeing machines have several drawbacks. First, floating the fabric in a bath of dye liquid to reduce the strain on the fabric requires a large amount of liquid relative to the amount of fabric to be dyed. The dye liquor to fabric weight ratio for most of these machines is 10:1 or more. Because the dyeing process frequently occurs under heat and pressure, the liquor volume must be heated, consuming an amount of energy proportionate to the amount of liquid contained within the vessel. At the conclusion of the dyeing process, the spent liquor is discharged as waste, incurring treatment costs proportionate to the amount of liquor in the vessel.
The older machines also often have problems with dye uniformity because the fabric rope 5 is under tension and often twisted by the lifter reel 23, by the jet venturi, or by the sharp turn that the fabric makes as it moves through the cloth discharge tube 20. This causes the dye in the jet to permeate the fabric rope unevenly. Fabric twists and tangles further complicate the dyeing process because they require shut-down of the machine in order to physically untangle the fabric. Moreover, all of the stresses and strains which are caused by prior art jet dyeing machines may damage light, more delicate fabrics by abrading the fabric.